Posts Tagged shoulder abduction
[Abstract] The Impact of Shoulder Abduction Loading on Volitional Hand Opening and Grasping in Chronic Hemiparetic Stroke
Background. Up to 60% of individuals with moderate to severe chronic hemiparetic stroke experience excessive involuntary wrist/finger flexion that constrains functional hand movements including hand opening. It’s not known how stroke-induced brain injury impacts volitional hand opening and grasping forces as a result of the expression of abnormal coupling between shoulder abduction and wrist/finger flexion or the flexion synergy.
Objective. The goal of this study is to understand how shoulder abduction loading affects volitional hand opening and grasping forces in individuals with moderate to severe chronic hemiparetic stroke.
Methods. Thirty-six individuals (stroke, 26; control, 10) were recruited for this study. Each participant was instructed to perform maximal hand opening and grasping forces while the arm was either fully supported or lifted with a weight equal to 25% or 50% of the participant’s maximal shoulder abduction torque. Hand pentagon area, defined as the area formed by the tips of thumb and fingers, was calculated during hand opening. Forces were recorded during grasping.
Results. In individuals with moderate stroke, increasing shoulder abduction loading reduced the ability to maximally open the hand. In individuals with severe stroke, who were not able to open the hand, grasping forces were generated and increased with shoulder abduction loading. Stroke individuals also showed a reduced ability to control volitional grasping forces due to the enhanced expression of flexion synergy.
Conclusions. Shoulder abduction loading reduced the ability to volitionally open the hand and control grasping forces after stroke. Neural mechanisms and clinical implications of these findings are discussed.
This pilot study tested the effectiveness of an intense, short-term upper-limb robotic therapy for improvement in motor outcomes among chronic stroke patients. We enrolled 30 subjects with upper-limb deficits due to stroke of at least 6 mo duration and with a Motor Power Assessment grade of 3 or less. Over 3 wk, 18 sessions of robot-assisted task-specific therapy were delivered with the use of a robotic exercise device that simulates a conventional therapy known as skateboard therapy.
Primary outcome measures included reliable, validated impairment and disability measures of upper-limb motor function. Statistically significant improvements were observed for severely impaired participants when we compared baseline and posttreatment outcomes (p < 0.05).
These results are important because they indicate that improvement is not limited to those with moderate impairments but is possible among severely impaired chronic stroke patients as well. Moderately and severely impaired patients in our study were able to tolerate a massed-practice therapy paradigm with intensive, frequent, and repetitive treatment. This information is useful in determining the optimal target population, intensity, and duration of robotic therapy and sample size for a planned larger trial.